Scientific Method and Experimental Design

Objectives Understand the purpose of the scientific method Be able to create a hypothesis from a problem or question Design a controlled experiment Identify dependent and independent variables Understand the purpose of data tables and graphs Know how to improve the accuracy of an experiment

Controlled Experiment Key Vocabulary Scientific Method Hypothesis Controlled Experiment Control Group Experimental Group Independent Variable Dependent Variable Constants Theory

Create an experiment to figure this out: You want your tomato plants to grow more tomatoes than your neighbor. You go to the store and see good looking fertilizer called “Joe’s Fertilizer.” You ask yourself, “Will Joe’s Fertilizer make my tomato plant grow more tomatoes?” Do Now Begin with this question and see what students know about creating a hypothesis and designing an experiment.

Controlled Experiment? What do you need for a valid scientific experiment? Problem Research Lets take a look at this stuff Hypothesis Experiment Brainstorming section (Problem to be figured out, Research (demo on importance), Hypothesis, Experiment, Observations & Data Collection/Review, and Conclusion) Data Collection/Organization Conclusion

Creating a Hypothesis Smithers thinks that a special juice will increase the productivity of workers (cut more paper). He asks himself, will this special juice increase my workers productivity? What would be a good hypothesis? If workers drink the special juice, then they will cut more paper. If workers don’t drink the special juice, then they will cut more paper

Creating a Hypothesis Johnson wonders if radio waves will make his mouse stronger for a race coming up. He asks himself, will radio waves make the mouse faster? What would a good hypothesis be? What would be a good hypothesis? If mice receive radio waves, then they will run faster. If mice receive radio waves, then they will run slower If mice do not receive radio waves, then they will run faster. If mice do not receive radio waves, then they will run slower.

Creating a Hypothesis Hypothesis Is a prediction or a guess as to what will happen Use your question to create a specific hypothesis Hypothesis: NEVER a question!!**** ALWAYS a Prediction! (what might happen) ALWAYS testable and measurable! In other words, stated as: “If ___(I do this)____, then ___(this)____ will happen.” A hypothesis serves as a basis for determining what data to collect when designing an experiment.

Do Now - Hypothesis Practice Complete page 7 “Creating Hypotheses”

Creating a Controlled Experiment

Controlled Experiment Terms Experiment where only ONE thing is changed to see if it has any effect Experimental group Group that receives the thing being tested (contains/has the new thing or condition) Control group (Key words = same, usual, ordinary, not changed) The usual, normal, dull, ordinary group This group is the comparison group to see if the thing or condition being tested had any effect Everything is the same as the experimental group except one thing (independent variable)

What is the experimental and what is the control group? Jason wanted to see if putting old coffee grinds at the base of his rose bushes would help her grow more roses. He had two groups, group 1 and group 2. Both groups had 10 rose bushes each in normal soil, watered with the same amount of water (1 cup/day), same amount of sunlight (6 hours/day) and both groups had the same species/type of roses. Group 1 had had no coffee grinds added like usual, but group 2 had coffee grinds added to the plants. Control Group – Experimental Group –

Controlled Experiment Terms Independent variable The ONE thing that is changed! The variable that is changed on purpose. Dependent variable The variable that’s measured to see your results. (Ex: height, speed). Depends on independent variable. Constants Factors that remain the same for both groups (the experimental and control group) After this slide, more experimental design practice.

Controlled Experiment What is needed for a good experiment? Large sample size (amount of test subjects) Repeated trials A control (or comparison) group Only ONE variable (thing) is changed What can be done to make an experiment more accurate or reliable (valid)? Increase the amount of test subjects Repeat the experiment In summary, what is needed for a good experiment? Have students think about what they learned. Is this measureable? Yes…you can measure the grades

Creating a Controlled Experiment Design and carry out a controlled experiment This is a test/series of tests to see if you hypothesis is right or wrong Smithers thinks that a special juice will increase the productivity of workers (cut more paper). He asks himself, will this special juice increase my workers productivity? What would be a good hypothesis & experiment? Introduce control and experimental group…. Go over independent and dependent variable again

Create a Hypothesis & Design a Controlled Experiment Identify the control group and experimental group(s). Everyone uses a Duracell battery, but does a Duracell battery last longer than an Energizer battery? You can have more than 1 experimental group!

Identify the control group and experimental group(s). I usually use white light for my plants. I want to know if using green light would help my plants grow taller. You can have many experimental groups

Experimental Design practice Page 8 #1-5 LP 4 -----Start----- (Review these 5 problems from last class)

Do Now Complete “section B” on page 14 #3 = independent variable 1.6

Do Now Complete # 6, 7 ,8 on page 15 End here LP 4

Do Now Complete # 1 – 3 on page 15

Observations and Data Collection Graphs and data tables? Make observations using tools (rulers, stop watch etc…) Take data and organize it into a table / graph Purpose: Graphs are used to organize data and see the results more clear in order to make a conclusion Bar (Shows comparisons) Line (shows relationships)

Do Now Complete # 54 & 55 on page 12 #15 on page 7

Do Now Page 15… # 4, 5, 9 - 13

Conclusion Conclusion: See if your conclusion supports of refutes your hypothesis (see if your hypothesis is right or wrong) If right or wrong, you still learn something!! In a laboratory, spinach leaves exposed to continuous fluorescent light increased in vitamin content by 50 to 100 percent. Spinach leaves kept in darkness for a similar period of time either lost vitamin content or produced no gain. Describe how these findings could influence the way in which spinach is displayed for sale in supermarkets. What’s your conclusion? 1.7

Repeat Repeat… Repeat or redesign the experiment and share with others! Why might it be important to repeat an experiment? Increase the accuracy / validity of the experiment Why might it be important to share scientific knowledge? So scientists can learn from one another The scientific body of knowledge grows faster To solve problems faster So other scientists can test your experiment and see if it’s right or wrong… increased accuracy!

Theory An explanation, supported by many experiments and lots of evidence, that can be used to accurately explain related occurrences. Strong Theories – Heliocentric Theory, Plate Tectonic Theory, Evolution, Cell Theory All scientific explanations are tentative and subject to change and improvement

Do Now Complete Regents Question Page 17 #14 & 16 Page 18 #17-19 Begin here if students had extra time and finished #1 on page 8. If students did not finish #1, begin with #1.

Do Now Page 13 (Review - Experiment analysis ) Take your time and really read the questions Begin here if students had extra time and finished #1 on page 8. If students did not finish #1, begin with #1.